1. Field of the Invention
The present invention relates to a system for controlling an industrial robot in association with a rotary table.
2. Description of the Related Art
In the prior art, there is already known an industrial robot which is operated in association with a rotary table mounted with a workpiece. This simplifies the movement on the robot side, speeds up the work, and enables greater compactness. Sometimes, a transfer means is annexed to either the robot or the rotary table.
In such a conventional robot apparatus, the robot or rotary table itself is mounted on the transfer shaft of the traveling means. That is to say, a very heavy article is moved. As a result, the transfer shaft and traveling means become large in scale and it is difficult to ensure precision. Further, a large space is necessary for the operation of the traveling means along the transfer shaft. Still further, there are limitations on the disposition of the transfer shaft and the need for adjustment of the positional relation with peripheral equipment.
In another prior art robot apparatus, teaching data is stored in the form of values on a specific coordinate system (absolute coordinate system) of the robot or in the form of displacement (angles) on each axis of the robot. When this teaching data is used for playback, the interpolative calculations carried out in consideration of the relative movement between the robot and rotary table becomes much more complicated and the overall computation time becomes longer. It is not possible to reduce the interpolation time, so there is a problem of reduced precision of the path. Moreover, there is the disadvantage that the data representing the shape of each workpiece varies with the position of the workpiece with teaching data of the absolute coordinate system. There is a further disadvantage that, when the relative position between the rotary table and the robot is changed due to a change in the position of installation of the robot or the rotary table, the teaching data becomes inaccurate and must be revised.